chore(performance): Enable the "union" feature on SmallVec #9772
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This feature is not enabled by default. From the docs: When the union feature is enabled smallvec will track its state (inline or spilled) without the use of an enum tag, reducing the size of the smallvec by one machine word. Signed-off-by: Bruce Guenter <bruce.guenter@datadoghq.com>
bruceg
added
type: tech debt
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@bruceg do you know why they don't enable it by default? I'm wondering what the trade-off is. |
I believe the only downside is it requires rust 1.49. |
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Using the union would likely lead to (slightly?) more complex code. According to the initial PR for the union feature servo/rust-smallvec#94 there is a performance hit in one of their tests, though most show better performance. Other than that, I don't know |
This feature is not enabled by default. From the docs: When the union
feature is enabled smallvec will track its state (inline or spilled)
without the use of an enum tag, reducing the size of the smallvec by one
machine word.
Signed-off-by: Bruce Guenter bruce.guenter@datadoghq.com